/**
 * 生成指定位数随机字符串
 * @param n  想要字符串的位数
 * @returns {string}
 */
function randomString(n) { //生成知道位数随机字符串
    let str = 'abcdefghijklmnopqrstuvwxyz9876543210';
    let tmp = '',
        i = 0,
        l = str.length;
    for (i = 0; i < n; i++) {
        tmp += str.charAt(Math.floor(Math.random() * l));
    }
    return tmp;
}
module.exports = randomString
